The present invention relates to a new and improved construction of marine reversing gearing or power transmission system for vessels or the like.
The marine reversing gearing of the present invention is of the type comprising a drive shaft, a forward clutch, a forward pinion arranged essentially coaxially with regard to the drive shaft and capable of being coupled therewith, during forward travel, by means of the forward clutch. There are also provided two intermediate gears which continuously mesh with the forward pinion, two intermediate pinions which are fixedly or rigidly connected with a respective one of the intermediate gears, a large gear which continuously meshes with both intermediate pinions, a reverse clutch, a rearward pinion which is coaxially arranged with regard to the drive shaft and can be coupled therewith, during rearward travel, by means of the reverse clutch, and two reversing pinions which are driven by the rearward pinion.
A prior art marine reversing gearing of this type, for instance as disclosed in U.S. Pat. No. 2,741,351, particularly FIGS. 3, 4 and 5 thereof, has the rearward pinion meshing with one of the reversing pinions and such being coupled by means of an additional clutch with the second reversing pinion. The additional clutch is always disengaged whenever the forward clutch is engaged, and is furthermore always engaged when the reverse clutch is engaged. The second reversing pinion meshes continuously with the same intermediate gears with which there also continuously mesh the forward pinion. These intermediate gears are thus provided for power transmission during rearward travel as well as during forward travel. While, however, during forward travel there is accomplished directly at the forward pinion a branching-off of the power, so that its group of gears which mesh with both of the intermediate gears only are loaded with a respective one-half of the drive power, during reverse travel there does not yet occur any branching-off of the power at the rearward pinion, since such must transmit the entire power to the first reversing pinion. The high loading of the rearward pinion and the first reversing pinion, occurring during rearward travel, renders it impossible to allow a vessel equipped with the heretofore known type of marine reversing gearing to travel rearwardly at full load or power output over a longer period of time. In the meantime vessels have been designed for fulfilling particular purposes, especially ice breakers, which throughout their period of use can travel approximately equally as long in reverse direction as in forward direction and during the rearward travel require the same drive power as during forward travel.